The present invention relates to a manufacturing method of high purity copper sulfate including the steps of dissolving commercially available copper sulfate crystals (purity, for instance, is 95 to 99.9 wt %) in purified water or acid, and thereafter removing impurities, and to the high purity copper sulfate obtained thereby. The starting raw material does not have to be copper sulfate crystals, and may be a resultant solution of dissolving copper in acid containing sulfuric acid, or copper sulfate crystals manufactured therefrom.
Copper sulfate (Cu2SO4) is a white-colored powder, but this generally refers to as a pentahydrate (CuSO4-5H2O), and is an azurite blue crystal.
Copper sulfate is being used as an electrolytic solution, pigment, insecticide, antiseptic, mordant, battery material, medicine and so on. In particular, when copper sulfate is to be used as the electroplating solution for electronic components such as a semiconductor device, high purity copper sulfate is sought after. Commercially available copper sulfate has a purity level of 95 to 99.9 wt %, and it is necessary to purify this further in order to realize a purity level of 4N to 5N or higher.
As conventional technology, disclosed is a method of obtaining copper sulfate with low Ni content by using electrolytic copper powder, which was electrodeposited and collected from an electrolytic solution, as the raw material, dipping this in acid to selectively dissolve and remove Ni, filtering the resultant solution and thereafter dissolving the copper powder in sulfuric acid to realize crystallization (e.g., refer to Japanese Patent Laid-Open Publication No. 2001-10817).
Further, also disclosed is technology for obtaining copper sulfate with a low nickel content by making copper sulfate containing nickel into an aqueous solution, heating this to 80° C. or higher, and collecting the copper sulfate crystals that are separated and settled as a result of the heating in order to realize concentrated recrystallization (e.g., refer to Japanese Patent Laid-Open Publication No. 2001-31419).